I used to have one of those boats (my first fishing boat). It cracked at the same spot as well as later in the bow (or keel? I'm not sure the correct term) along the seam (just in front of where yours is painted brown). Looks like yours has had a couple poor quality repairs already done to it. I used a similar repair kit and it held up for a few years until I sold the boat. My boat lived in NM and AZ for years and was out uncovered in the hot sun for more than a decade before I picked it up -- the fiberglass got brittle which was causing the problems. The good news is I absolutely know that the boat will float half full of water
. Good luck and wear a life jacket...you might need it.
By the way, if I were repairing it I'd completely sand off the old patches and fill in the gaps with an epoxy mixed with a filling compound. Then I'd sand it into shape and then epoxy on a fiberglass patch on both the inside and outside of the boat over the crack. If you just put a cheap patch on over the crack there will be movement and the patch will fail. By filling it you give the patch a solid surface to cover and it will be far more effective.